The subject invention is directed to the art of earth-working equipment and, more particularly, to a method and apparatus adapted for particular use in burying an elongated flexible member such as a plastic drainage pipe or cable a predetermined distance beneath the surface of the soil.
Typically, in the past, plow assemblies of the general type under consideration have had a narrow, rigid plow unit mounted at the lower end of a heavy support member. Through the application of great force, the plow was pulled through the soil forming a narrow, slit-like trench area into which the flexible pipe was fed at a position immediately behind the plow. The problem with this general type of plow unit was the great force required to move the plow through the soil. Additionally, the soil at the trench bottom and at the lateral sides adjacent the bottom was often heavily compacted. Thus, the naturally occurring small passages and capillaries in the soil which are necessary to permit the flow of soil water to the drain pipe were destroyed. Plow assemblies of this general type are shown, for example, in U.S. Pat. Nos. 3,425,232; 3,429,134; 3,528,255; 3,684,030; 3,699,693; and, 3,726,099.
In U.S. Pat. No. 3,706,207, issued Dec. 19, 1972, to Cornelius, et al., it was proposed to provide a plow having an oscillatory or cyclically moving front edge for the purpose of reducing the force required to move the plow through the soil and for reducing the aforementioned soil compaction problems. With the Cornelius, et al. type apparatus, however, the oscillatory or cyclical movement disclosed is harmonious and carried out through a relatively limited range. While the structure disclosed in Cornelius, et al. would probably provide some degree of improved results, the plow pulling force required and the resulting soil compression would most likely still be at undesirable levels. Moreover, Cornelius, et al. does not take other design criteria into consideration necessary to achieve the desired end results and operating parameters.